Touring car racing takes a lot of skill, patience, and work. I have been racing touring cars for two seasons (although not many races per season) and I am still one of the slower guys on the track. Just try to run a good steady line and do not try to catch up to faster drivers. Start the turns high and finish them low. The things you should be most concerned with are avoiding crashes and running a decent line at a steady pace. Do not worry about the people that are passing you. If you follow these instructions you will probably finish a little less than mid pack. A large number of people crash out.
The most important parts of your setup will be tires, gearing, camber, toe, springs, ride height, and steering angle. Settings like bump stop, droop, ackerman, caster, tweak, track width, wheelbase, roll center, shock angle, shock oil, etc are used to dial-in your ride (although they are important). Make sure your tires wear evenly, if they cone you will have no traction.
I find off-road racing to be much easier than on-road. Off-road leaves much more room for error while on-road is very precise.